Battery life in a hearing aid is a crucial feature, as changing battery is difficult for users with poor dexterity. Moreover, users with a poor vision have problems changing batteries as the batteries are often small and as the holder into which the battery is inserted is also very small.
Moreover, hearing aids that are adapted to be inserted completely into the auditory canal of the user and remain there for longer periods (e.g., years) will benefit from improved battery life, as the period between changing hearing aids will be extended.
Thus, there is a need for improving the battery life of batteries in hearing aids. Improvement of the battery life may be achieved by providing better batteries or by improving the power consumption of the hearing aid.
Background art may be found in U.S. Publication No. 2005/0226446, which discloses a hearing aid that is capable of automatically switching between a full-function mode and a sleep mode depending on the location of the hearing aid. The hearing aid comprises a hearing aid module for processing an input signal and generating a compensated output signal and, a location sensor module for providing a location information signal to indicate one of an in-the-ear case and an out-of-the-ear case. The hearing aid module automatically switches to the full-function mode when the location information signal indicates the in-the-ear case and the hearing aid module automatically switches to the sleep mode when the location information signal indicates the out-of-the-ear case.
A drawback of a switching scheme based on determining in or out of the ear is that this can result in a false power down, for example, when the hearing aid is only taken out shortly, such as when to reposition the hearing aid. Moreover, this only works for hearing aids that are taken out daily or at least regularly. Use of additional sensors to prevent false power down has been proposed, e.g. U.S. Pat. No. 6,330,339 discloses the use of complex sensors for brain wave or pulse. However, this requires additional processing steps of determining a condition before determining to power down or up, resulting in complex power management schemes.
It is an object of one or more embodiments of the present invention to provide a hearing aid in which the time between battery changes is extended.